Guns for NSC and OPC–MilitaryAeroSpace–OPC Displacement

MilitaryAeroSpace is reporting that the Navy has issued a $16.4M contract for two 57mm Mk110 gun systems to equip an NSC and an OPC. There are no surprises here, but there is the most exact figure I have seen for the displacement of the Offshore Patrol Cutter, 3,730 tons. Presumably that is a full load displacement.

We knew the OPC was going to be bigger than the WMECs they replace, and I have published estimates as high as 4,000 tons. But how large is this, compared to our existing ships?

  • More than 3.5 times as large as a 210.
  • About 2.1 times as large as a 270.
  • 27% larger than the Alex Haley.
  • 22% larger than the WHEC 378s.

These are going to be very substantial ships.

7 thoughts on “Guns for NSC and OPC–MilitaryAeroSpace–OPC Displacement

      • Depending on the period that is about right. The 327s went through a lot of changes that yielded different full load displacement, but I have an 82/83 Janes that provides a full load as they were late in their lives. It indicates a full load displacement of 2,656 tons, meaning the OPC will be 40.4% larger Hope they are as good and as successful as the 327s.

  1. CRS Ronald O’Rourke quote taken from “Coast Guard Cutter Procurement: Background and Issues for Congress–Nov. 30, 2017” report

    “The detailed design for the OPC is now being developed. As of May 26, 2017, the OPC’s light ship displacement (i.e., its “empty” displacement, without fuel, water, ballast, stores, and crew) was preliminarily estimated at about 2,640 to 2,800 tons, and its full load displacement was preliminarily estimated at about 3,500 to 3,730 tons.”

    Info was supplied by USCG liaison office May 26, 2017, if actual figures are released after delivery in 2021 will be of interest to see how numbers compare to estimate:)

      • The Navy at one time followed their 1986 standard for Service Life Allowances, SLAs, to be included in all new ships and modified repeat designs, such as when delivered to be capable of accommodating the anticipated growth of weight and KG during its service life without compromise of the hull strength, reserve buoyancy and stability characteristics established for the class.

        Ships as they get older inevitably get heavier and become less stable, as new equipment and systems are added above the center of gravity. The Navy for those overweight Burkes have to ensure stability use the cheap fix of adding lead or pig iron ballast at the cost of degrading performance, speed, range and lowering the V-line of the ship, where your openings are and not have free communication to the sea.

        The Navy SLA standard for surface combatants is 10% for weight growth and 12 inches for KG (totally ignored for both classes of LCSs), if USCG specified Navy SLA standard applied to the OPC at heaviest current estimated FLD 3,730 tons, the designed EOL max. displacement could be 4,100 tons, so your original estimate of 4,000tons looks good 🙂

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